Increasing the ion content of the air within a room can be desirable for a variety of reasons. For example, a high negative ion content freshens the air and has beneficial physiological effects on persons who breathe the air. Air ions of either polarity act to remove dust, pollens, smoke and the like by imparting an electrical charge to such particulates. The charged particles are electrostatically attracted to walls or other nearby surfaces and tend to cling to such surfaces.
Some usages of air ionizers require production of both positive and negative ions. Most notably it has been found that a high concentration of both types of ion acts to suppress accumulations of static electricity on objects in a room. Static electrical charges attract air ions of the opposite polarity and the attracted ions then neutralize the static charges. This can be of particular value in certain industrial operations such as in the clean rooms where microchips or other miniaturized electronic components are manufactured. Accumulations of static charge attract contaminants to such products and may also directly damage a microchip or the like.
An advantageous type of ionizing device has sharply pointed electrodes to which high voltages of the order of several thousand volts are applied and which are exposed to the ambient air. Positive and negative high voltages are applied to separate electrodes or are alternately applied to the same electrode. The resulting intense electrical field near the pointed end of the electrode converts the nearby molecules of the constituent gases of air into positive and negative ions. Ions with a polarity opposite to that of the high voltage are attracted to the electrode and neutralized. Ions of the same polarity as the high voltage are repelled by the electrode and by each other and disperse outward into the surrounding air. Dispersal of the ions is usually accelerated by directing an airflow through the electrode region and out into the room.
The positive and negative ions in the air flow should be thoroughly intermixed if the apparatus is to suppress static charges on objects rather than creating such charges. This condition is not met immediately since the ions of different polarity are produced at separated electrodes or at different time periods at the same electrode. Such intermixing does occur gradually as the airflow progresses away from the ionizing apparatus but it has heretofore been necessary to keep the ionizer a sizable distance away from objects that are to be protected to avoid subjecting the objects to incompletely mixed concentrations of ions of one polarity. It would be more convenient in many instances if the ionizer could be closer to the objects on which static charge is to be suppressed.
The present invention is directed to overcoming one or more of the problems discussed above.